246 INSECTS INJURIOUS TO STAPLE CROPS. 



amount of food out of all proportion to their size, the 

 larv8B have become full-grown, and enter the earth, where 

 they form smooth, oTal cells, and transform to the pup^. 

 In a week or two the adult beetles emerge from the pupal 

 skins and after feeding for a couple of weeks, deposit eggs 

 for another brood. The life-history of this brood is the 

 same, except that the time required for it is less than for 

 the first, and following it comes the third brood, the 

 beetles of which hibernate over winter as already described. 

 The time required for the development of a brood is 

 exceedingly variable, and owing to the length of time 

 required for laying the eggs, and the fact that some larv« 

 become full-grown much more quickly than others, all 

 stages of the insect may be found during the summer 

 months. 



^ 



Fig. 140. — Tacliinid Parasite of Colorado Potato-beetle {Lydelta, 

 dorypliorce Ril.). (After Riley.) 



Natural Enemies. — One of the chief agencies to prevent 

 the excessive multiplication of this j^est is the weather. 

 Thus, Professor Otto Lugger records that in Minnesota, 

 late in the fall of 1894, the beetles were lured from their 

 winter quarters by a few warm days, and most of them 

 subsequently perished from hunger or frost. In addition 



